$ A = \left[\begin{array}{rrr}3 & 4 & 9 \\ 2 & 3 & 9 \\ 4 & 4 & 9\end{array}\right]$ What is $ A^{T}$ ?
Explanation: To find the transpose, swap the rows and columns. $ A^{T}$ = $\left[\begin{array}{rrr}3 & 2 & 4 \\ 4 & 3 & 4 \\ 9 & 9 & 9\end{array}\right]$